As a background art of the present technical field, disclosed is JP-A-2007-304263 (Patent Literature 1), for example. In this publication, “to provide a holographic memory device that can execute control such that reproduced light emitted from a reproduction target hologram passes through a polytopic filter appropriately” is described as a problem to be resolved and “a part of reproduced light emitted from a holographic memory 10 is split by a beam splitter. After astigmatism is introduced into the split reproduced light by a condensing lens 126 and a cylindrical lens 127, the reproduced light is received by a quadripartite PD 128. FE signals, RE signals, and TE signals are generated by an operation circuit, on the basis of signals from the quadripartite PD 128. In addition, the holographic memory 10 is driven in a focal direction, a radial direction, and a tangential direction, on the basis of the signals, and a position of the reproduction target hologram is corrected with an appropriate position” is described as a solution.